One presently known type of undercarpet cable system includes a flat multiconductor cable which is assembled between a plastic shield and a metallic shield. The cable assembly, comprising the cable and its two protective shields, is installed between a floor and overlying carping. The multiconductor cable includes a plurality of flat electrical conductors which are contained in a casing comprised of a thin sheet of electrical insulation. The plastic shield provides a cushion for the multiconductor cable so as to resist the abrasion and possible piercing of the cable insulation by projections extending upwardly from the floor, such projections being especially prevalent if the floor is made of concrete or a similar coarse building material. The metallic shield resists piercing of the cable insulation by an object inserted through the carpet. By electrically grounding the metallic shield, any electrically conductive object which may pierce the metallic shield and contact a "hot", i.e., electrically energized, conductor of the multiconductor cable will be grounded so as to protect a person who contacts the object from electrical hazard.
Inasmuch as the multiconductor cable and the two shields may not be positively attached to each other either before, during or after their installation, there is the possibility that the cable could be installed without the shields or that, once installed, the shields could move relative to the cable, thereby leaving a portion of the cable exposed either aside the metallic shield or the plastic shield. Such exposed cable runs a greater risk of being pierced than a properly covered cable and, therefore, presents an electrical hazard.
Where the metallic shield is properly positioned above the cable, there remains the possibility that the metallic shield will not be properly grounded, for instance, by failure to electrically connect it to ground. Like a properly grounded shield which is improperly installed so as to expose a portion of the cable, a cable having a nongrounded metallic shield presents a potentially hazardous situation.
Such known undercarpet wiring system includes a network of cable assemblies, the individual cable assemblies being electrically connected. In such a system, the metallic shield of each assembly is grounded by use of connectors for electrical connection of adjoining metallic shields. In such arrangement, shield grounding integrity is dependent on physical continuity of the shield. Thus, if the shield is interrupted as by cutting, the free remnant of the shield will not be electrically continuous to ground, with resulting hazard.
In such known system, connections between cables are made, in tap or splice configuration, by arranging the cables in mutually abutting relation. For instance, a tap connection of two five-conductor cables is prepared by arranging the five conductors of a first cable perpendicular to the conductors of a second cable and in abutment with a side margin of the second cable. Insulation-piercing connectors are now placed beneath each conductor of the first cable, each connector being of different size from all others so as to extend into registry under a different conductor of the second cable. The connections are then crimped into electrical engagement with each cable. Difficulty attends this practice, particularly in the need for such different size connectors and the fact that all but one of the connectors span plural conductors of the second cable, giving rise to possible interphase short circuitry.